Preparation Of Iron-based Composite Materials Based On Persulfate And Its Removal Efficiency Of R Eactive Black 5

Advanced oxidation technology based on persulfate has great application potential.Currently,iron-based catalysts are commonly used to activate persulfate,but most of them are prone to agglomerate,produce a large amount of sludge to affect the effluent water quality,and the effective electron utilization efficiency of the iron phase is not high,which affects the removal of organic pollutants.Therefore,it is necessary to develop new iron-based catalysts.In this paper,two catalysts were prepared by different methods,and characterized by XRD,XPS,FTIR,TEM or SEM,BET instruments.With active black 5 as the target pollutant,the naphthalene ring structure and azo chromophore structure at 310 nm and 597 nm were studied under different influencing factors such as catalyst dosage,persulfate dosage,initial pH,inorganic anions,etc.Considering the function of reactive oxygen species and iron,the catalytic mechanism was discussed,and the recycling characteristics of the catalyst were investigated.The following conclusions are obtained:(1)The mesoporous carbon-iron core material(Fe@HC)was successfully prepared as a PS activator using the "hydrothermal+high temperature pyrolysis" two-step method.The specific surface area is 280.7 m2/g,the average pore size is about 5.1 nm,and the cumulative total pore volume of BJH adsorption is 0.284 cm3/g;compare to Fe@HC or PS alone,the coexistence of Fe@HC and PS can efficiently remove RB5,the decolorization rate is 99.2%,and the naphthalene ring destruction rate has also reached 61.8%,the removal process conforms to second-order kinetics;the overall removal effects of RB5 increasing with Fe@HC and PS dosage.The naphthalene ring and decolorization rate are always higher than 62%and 86%in the range of pH 3-11 in the Fe@HC+PS system,Cl-and SO42-have little effect on the removal efficiency,Fe@HC shows good anti-interference ability of the environment.The mechanism of Fe@HC activating PS to remove RB5 is mainly that the graphite carbon layer of the catalyst improves the electron utilization efficiency of the iron core,and they cooperate with each other to promote the generation of 1O2 in the system,thereby exerting the oxidative degradation effect.The cycle regeneration performance of Fe@HC is good.(2)The iron-modified straw material(ST/Fe)with network structure was prepared by immersion and freeze-drying with ferric chloride,and then was used to activate PS and remove RB5.Its specific surface area and surface functional groups provide conditions for the activation of PS,and the loaded iron mainly exist in the form of Fe3+and Fe2+;ST/Fe can effectively activate PS,and efficiently remove RB5 within 100 minutes,with a removal rate up to 87.4%;the removal effect of RB5 increases with ST/Fe dosage and PS concentration,but excessive PS will inhibit the removal of RB5;RB 5 removal effect under acidic conditions is better than neutral and alkaline conditions;and Cl-and SO42-will inhibit RB5 removal.The activated iron particles and straw in ST/Fe cooperate with each other to obtain reduced Fe2+,so that it can activate PS to produce SO4·-and ·OH to efficiently remove RB5.ST/Fe can be reused,and the initial catalytic removal performance of material is up to 191.2 mg/g.Therefore,in the degradation process of organic pollutants in wastewater,ST/Fe has certain application prospects as a PS activator.